12 Oracle Multimedia ORDSource Object Type

Oracle Multimedia provides the ORDSource object type, which supports access to a variety of sources of multimedia data.

It supports access to data sources locally in a BLOB within the database, externally from a BFILE on a local file system, externally from a URL on an HTTP server, or externally from a user-defined source on another server.

The ORDSource object type is defined in the ordsrcsp.sql file. After installation, this file is available in the Oracle home directory at:

<ORACLE_HOME>/ord/im/admin (on Linux and UNIX)

<ORACLE_HOME>\ord\im\admin (on Windows)

Note:

The ORDSource object type is used only by other Oracle Multimedia objects. This information is for reference use, only. Oracle recommends that you not use this type directly.

12.1 Important Notes for ORDSource Methods

Methods invoked at the ORDSource level that are handed off to the source plug-in for processing have ctx (RAW) as the first argument. Before calling any of these methods for the first time, the client must allocate the ctx structure, initialize it to NULL, and invoke the open( ) method. At this point, the source plug-in can initialize context for this client. When processing is complete, the client must invoke the close( ) method.

Methods invoked from a source plug-in call have the first argument as obj (ORDSource) and the second argument as ctx (RAW).

Note:

In the current release, none of the plug-ins provided by Oracle and not all source or format plug-ins use the ctx argument, but if you code as previously described, your application should work with current or future source or format plug-ins.

The ORDSource object does not attempt to maintain consistency, for example, with local and upDateTime attributes. It is up to you to maintain consistency. ORDAudio, ORDDoc, ORDImage, and ORDVideo objects all maintain consistency of their included ORDSource object.

12.2 ORDSource Object Type

The ORDSource object type supports access to a variety of sources of multimedia data. The attributes for this object type are defined as follows in the ordsrcsp.sql file:

localData: the locally stored multimedia data stored as a BLOB within the object. Depending on the block size, up to 8 terabytes (TB) to 128 TB of data can be stored as a BLOB within Oracle Database, and is protected by the Oracle security and transaction environment.

The return INTEGER is 0 (zero) for success and greater than 0 (for example, 1) for failure. The exact number and the meaning for that number is plug-in defined. For example, for the file plug-in, 1 might mean "File not found," 2 might mean "No such directory," and so on.

Pragmas

None.

Exceptions

ORDSourceExceptions.INCOMPLETE_SOURCE_INFORMATION

This exception is raised if you call the close( ) method and the value of the srcType attribute is NULL.

ORDSourceExceptions.METHOD_NOT_SUPPORTED

This exception is raised if you call the close( ) method and this method is not supported by the source plug-in being used.

12.3.3 deleteLocalContent( )

This method can be called after you export the data from the local source to an external data source and you no longer need this data in the local source.

Pragmas

None.

Exceptions

None.

Examples

None.

12.3.4 export( )

Format

export(ctx IN OUT RAW,
source_type IN VARCHAR2,
source_location IN VARCHAR2,
source_name IN VARCHAR2);

Description

Copies data from the localData attribute within the database to an external data source.

Note:

The export( ) method provides native support only for a source.srcType value of FILE. In this case, the data is exported to a file in a directory that is accessible to Oracle Database. User-defined sources can support the export( ) method to provide WRITE access to other types of data stores.

After exporting data, all attributes remain unchanged except the srcType, srcLocation, and srcName attributes, which are updated with input parameter values. After calling the export( ) method, you can call the clearLocal( ) method to indicate that the data is stored outside the database, and then call the deleteLocalContent( ) method to delete the content of the local data in the localData attribute.

When the source_type parameter has a value of FILE, the source_location parameter specifies the name of an Oracle directory object, and the source_name parameter specifies the name of the file in which the data is to be contained.

The export( ) method writes only to a database directory object that the user has privilege to access. That is, you can access a directory object that you have created using the SQL statement CREATE DIRECTORY, or one to which you have been granted READ and WRITE access.

For example, the following SQL*Plus commands create a directory object and grant the user ron permission to read and write to any file within the directory c:\mydir\work. Before executing these commands, you must be connected as a user with privileges to create a directory object.

An output parameter to receive the MIME type of the data, for example, audio/basic.

format

An output parameter to receive the format of the data, for example, AUFF.

duration

The life of the temporary LOB to be allocated. The life of the temporary LOB can be for the duration of the call, the transaction, or for the session. The default is DBMS_LOB.SESSION. Valid values for each duration state are:

DBMS_LOB.CALL

DBMS_LOB.TRANSACTION

DBMS_LOB.SESSION

cache

A Boolean value that indicates whether to keep the data cached. The value is either TRUE or FALSE. The default is TRUE.

Usage Notes

None.

Pragmas

None.

Exceptions

NO_DATA_FOUND

This exception is raised if you call the getContentInLob( ) method when working with temporary LOBs for looping read operations that reach the end of the LOB, and there are no more bytes to be read from the LOB. (There is no ORD<object-type>Exceptions prefix to this exception because it is a predefined PL/SQL exception.)

12.3.7 getContentLength( )

Format

getContentLength(ctx IN OUT RAW) RETURN INTEGER;

Description

Returns the length of the data content stored in the source. For a file source and for data in the localData attribute, the length is returned as a number of bytes. The unit type of the returned value is defined by the plug-in that implements this method.

User input needed by some sources to obtain the desired source address.

Usage Notes

Use this method to return the address of an external data source when the source must format this information in some unique way. For example, call the getSourceAddress( ) method to obtain the address for RealNetworks server sources or URLs containing data sources located on Oracle Fusion Middleware.

After importing data from an external data source to a local source (within Oracle Database), the source information remains unchanged (that is, pointing to the source from where the data was imported).

If the value of the srcType attribute is FILE, the srcLocation attribute contains the name of a database directory object which contains the file to be imported, and the srcName attribute contains the name of the file to be imported. You must ensure that the directory for the external source location exists or is created before you use this method.

The import( ) method reads only from a database directory object that the user has privilege to access. That is, you can access a directory object that you have created using the SQL statement CREATE DIRECTORY, or one to which you have been granted READ access.

For example, the following SQL*Plus commands create a directory object and grant the user ron permission to read any file within the directory c:\mydir\work. Before executing these commands, you must be connected as a user with privileges to create a directory object.

If the value of the srcType attribute is HTTP, the srcLocation attribute contains the base URL needed to find the source directory that contains the object to be imported, and the srcName attribute contains the name of the object to be imported.

This method uses the PL/SQL UTL_HTTP package to import media data from an HTTP data source. You can use environment variables to specify the proxy behavior of the UTL_HTTP package. For example, on Linux and UNIX, setting the environment variable http_proxy to a URL specifies that the UTL_HTTP package must use that URL as the proxy server for HTTP requests. Setting the no_proxy environment variable to a domain name specifies that the HTTP proxy server not be used for URLs in the specified domain.

If the value of the source.srcType attribute is a user-defined name, the source.srcLocation attribute contains an identifier string required to access the user-defined object to be imported, and the source.srcName attribute contains the name of the object to be imported.

Pragmas

None.

Exceptions

ORDSourceExceptions.INCOMPLETE_SOURCE_INFORMATION

This exception is raised if you call the import( ) method and the value of the srcType attribute is NULL.

ORDSourceExceptions.METHOD_NOT_SUPPORTED

This exception is raised if you call the import( ) method and this method is not supported by the source plug-in being used.

ORDSourceExceptions.NULL_SOURCE

This exception is raised if you call the import( ) method and the value of the localData attribute is NULL.

12.3.16 importFrom( )

importFrom(ctx IN OUT RAW,
mimeType OUT VARCHAR2,
format OUT VARCHAR2
source_type IN VARCHAR2,
source_location IN VARCHAR2,
source_name IN VARCHAR2);

Description

Transfers data from the specified external data source (type, location, name) to the localData attribute within the database, and resets the source attributes and the timestamp.

Parameters

ctx

The source plug-in context information. This information is passed along uninterpreted to the source plug-in handling the importFrom( ) call. (See Important Notes for ORDSource Methods.)

mimeType

The output parameter to receive the MIME type of the data, if any, for example, audio/basic.

format

The output parameter to receive the format of the data, if any, for example, AUFF.

source_type

The type of the source data to be imported. This also sets the srcType attribute. (See Table 7-1.)

source_location

The location from which the source data is to be imported. This also sets the srcLocation attribute. (See Table 7-2.)

source_name

The name of the source data to be imported. This also sets the srcName attribute. (See Table 7-3.)

Usage Notes

This method describes where the data source is located by specifying values for the type, location, and name parameters, which set the srcType, srcLocation, and srcName attribute values, respectively, after the importFrom( ) operation succeeds. This method is a combination of a setSourceInformation( ) method followed by an import( ) method.

If the value of the source_type parameter is FILE, the source_location parameter contains the name of a database directory object that contains the file to be imported, and the source_name parameter contains the name of the file to be imported. You must ensure that the directory indicated by the source_location parameter exists or is created before you use this method.

The importFrom( ) method reads only from a database directory object that the user has privilege to access. That is, you can access a directory object that you have created using the SQL statement CREATE DIRECTORY, or one to which you have been granted READ access.

For example, the following SQL*Plus commands create a directory object and grant the user ron permission to read any file within the directory c:\mydir\work. Before executing these commands, you must be connected as a user with privileges to create a directory object.

If the value of the source_type parameter is HTTP, the source_location parameter contains the base URL needed to find the source directory that contains the object to be imported, and the source_name parameter contains the name of the object to be imported.

This method uses the PL/SQL UTL_HTTP package to import media data from an HTTP data source. You can use environment variables to specify the proxy behavior of the UTL_HTTP package. For example, on Linux and UNIX, setting the environment variable http_proxy to a URL specifies that the UTL_HTTP package must use that URL as the proxy server for HTTP requests. Setting the no_proxy environment variable to a domain name specifies that the HTTP proxy server not be used for URLs in the specified domain.

If the value of the source_type parameter is a user-defined name, the source_location parameter contains an identifier string required to access the user-defined object to be imported, and the source_name parameter contains the name of the object to be imported.

Pragmas

None.

Exceptions

ORDSourceExceptions.METHOD_NOT_SUPPORTED

This exception is raised if you call the importFrom( ) method and this method is not supported by the source plug-in being used.

ORDSourceExceptions.NULL_SOURCE

This exception is raised if you call the importFrom( ) method and the value of the localData attribute is NULL.

The return INTEGER is 0 (zero) for success and greater than 0 (for example, 1) for failure. The exact number and the meaning for that number is plug-in defined. For example, for the file plug-in, 1 might mean "File not found," 2 might mean "No such directory," and so on.

Pragmas

None.

Exceptions

ORDSourceExceptions.INCOMPLETE_SOURCE_INFORMATION

This exception is raised if you call the open( ) method and the value of the srcType attribute is NULL.

ORDSourceExceptions.METHOD_NOT_SUPPORTED

This exception is raised if you call the open( ) method and this method is not supported by the source plug-in being used.

To successfully read HTTP source types, the entire URL source must be requested to be read. To implement a read method for an HTTP source type, you must provide your own implementation for this method in the modified source plug-in for the HTTP source type.

Before you call the import( ) method, you must call the setSourceInformation( ) method to set the srcType, srcLocation, and srcName attribute information to describe where the data source is located. If you call the importFrom( ) or the export( ) method, then these attributes are set after the importFrom( ) or export( ) call succeeds.

You must ensure that the directory indicated by the source_location parameter exists or is created before you use this method.

Pragmas

None.

Exceptions

ORDSourceExceptions.INCOMPLETE_SOURCE_INFORMATION

This exception is raised if you call the setSourceInformation( ) method and the value of the source_type parameter is NULL.

The return INTEGER is 0 (zero) for success and greater than 0 (for example, 1) for failure. The exact number and the meaning for that number is plug-in defined. For example, for the file plug-in, 1 might mean "File not found," 2 might mean "No such directory," and so on.

Pragmas

None.

Exceptions

ORDSourceExceptions.INCOMPLETE_SOURCE_INFORMATION

This exception is raised if you call the trim( ) method and the value of the srcType attribute is NULL.

ORDSourceExceptions.METHOD_NOT_SUPPORTED

This exception is raised if you call the trim( ) method and this method is not supported by the source plug-in being used.